Table of Contents
GENERAL INSTRUCTIONS
Auto-manufacturer's ue qu ве
Zero adjust .
Testing rotary (Wankel) engine E a.
Testing transistorized ignition systems .
UGS 2 0 5 снов ва ов ве
TACHOMETER
How to operate tachometer .
Idle speed and mixture setting .
Multiple barrel carburetors .
Adjusting fast idle speed . . .
Air fuel ratio test . . . .
Air filter test . .
Positive crankcase Ventslator (PCV)
Cylinder power balance test .
Distributor centrifugal advance test .
DWELL
How to use dwell angle meter .
Adjusting dwell angle . . .
Dual point distributors . .
Testing for dwell variation .
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ra GENERAL INSTRUCTIONS
AUTO-MANUFACTURER'S SPECIFICATION
Variation in specifications and wiring in a large number of cars and trucks
made it necessary to generalize this instruction manual. Use this manual as
guide line for the most commen. tests. For specific specifications, wiring
diagrams and instructions for various cars and trucks, refer to the
manufacturer's manual or a good automobile service manual.
ZERO ADJUST
Before using your analyzer always check that the meter reads on zero without
any of the test clips connected to the vehicle. If it doesn't use a small
screw-driver to turn the zero adjuster in the opening on the front of the meter
left or right slightly until the meter pointer rests on zero. This adjustment
assures you the maximum accuracy that was built into your tester's circuit.
TESTING ROTARY. (WANKEL) ENGINES
This instrument may be used on rotary engines equipped with point controlled
ignition systems.The design of this type of engine provides for one spark plug
firing per crankshaft revolution. To read correct RPM and DWELL refer to the
following table:
Number of rotors 2 3 4
Read RPM and DWELL on scale for 4 cyl. 6 cyl. 8 cyl.
conventional engine with: $
The point function tests are read in the same manner as conventional systems.
TESTING TRANSISTORIZED IGNITION SYSTEMS
BREAKER POINT SYSTEMS:
There are a great variety of transistorized ignition systems, and it would
not be possible or practical to list them all. Fortunately, the systems are
basically the same in that the heavy coil current is carried by a Transi-
stor, instead of the contact points. Unless otherwise specified by the
manufacturer, the best connection for the test clips is across the points.
A typical system and clip connections for tach/dwell/points readings are
shown in Fig. 1.
IGN SW IGN SW
E of wns]
Fig. 1 BALLAST Fig. 2 BALLAST
TRANSISTOR PE bypass
UNIT BALLAS
© <. black (4)
L DIST __] MAGNETIC DIST
| BATTERY
NOTE: For positive ground systems reverse the RED and BLACK clip connections.
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MAGNETIC PULSE SYSTEM -l-
In this system, a magnetic generator built into the distributor produces a
pulse that operates the transistor. The tachometer leads are connected
across the transistor in this system as shown Fig. 2. THE DWELL METER AND
POINT RESISTANCE TESTS ARE er PERFORMED ON MACNETIC PULSE SYSTEMS since
there are no points.
MAGNETIC PULSE SYSTEM -2-
This transistorized ignition system can be identified by the double primary
wire leading to the distributor, a dual ballast resistor, and control unit.
RPM readings are obtained by connecting the red clip to the negative terminal
of the ignition coil and the black clip to ground.
MAGNETIC PULSE SYSTEM -3-
This system has the ignition coil mount ed directly onto e distributor cap.
To read engine RPM, connect the red clip to the tachometer terminal provided
on the distributor (adaptor may be used) and the black clip to ground.
CAPACITIVE DISCHARGE (CD) SYSTEM:
Some capacitive discharge systems are provided with a lug to y which tachometer
can be connected. On other systems, the tachometer can usually be connected
from ground to the primary wire leading to the breaker points, or in some
case, from ground to the coil primary. Consult the manufacturer's
specification,
TESTS:
All tests are run witH the engine at normal operating temperature unless stated
BEFORE DOING ANY TUNE-UP OR TEST, WARM THE ENGINE TO ITS NORMAL
WITH THE BUTTERFLY CHOKE FULLY OPEN AND THE FAST IDLE
atherwise.
OPERATING TEMPERATURE.
CAM IN SLOW POSITION.
TACHOMETER
Tachometer is used to measure engine RPM. It is used while adjusting id
and mixture setting. The tachometer also may be used to make tests of the PCV
system, cylinder power balance, carburetor's air fuel ratio setting, air cleaner
efficiency and distributor's mechanical advance.
le speed
HOW TO OPERATE TACHOMETER (See Fig. 3 for typical connections)
l. Move the function switch to LO-RPM (Lo-Tach or Tach) or HI-RPM (Hi-Tach)
position depending upon the test to be made.
2. Move the cylinder switch (If yur analyzer provides one) to the number of
cylinders required.
3, Connect the BLACK clip to a good engine or chassis ground.
4. Connect the RED clip to the distributor terminal of ignition coil.
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>. Start the engine and read engine RPM on the appropriate meter scale.
Fig. 3
TO IGNITION SWITCH =
BLACK
COIL
NOTE: For positive ground systems reverse the RED and BLACK clip
connections, ‘
IDLE SPEED AND MIXTURE SETTING
1. Remove the air filter.
2. With engine running and at its operating temperature, clear the
carburetor with a couple mild jabs of the accelerator, then let it return
to idle.
3. Turn the carburetor's idle mixture screw in (leaning the mixture) until
engine RPM begins to fall off. Then slowly turn the idle mixture screw out,
the engine RPM will increase and then begins to drop off with further
outward turning. Adjust the screw in and out between these two fall-off
points so as to obtain the highest steady RPM ("peak" RPM). Missing or
rolling is a sign of too lean or too rich.
4. After an idle mixture set adjustment, re-set the idle speed as necessary
to hold engine speed within 50 RPM of the manufacturer's recommendation
for idle speed.
NOTE:
a. Above is the proper idle speed and mixture setting for pre-emission
controlled vehicles. On engines with emission controls, do not remove
idle mixture plastic cover if fitted. On all American vehicles
manufactured since 1968 after completing the step 3., turn the idle
mixture screw in (clockwise) until engine speed drops 50 RPM or the
amount specified by the manufacturer.
b. There is a considerable variation between car manufacturers regarding
the conditions for setting final hot idle speed. Consult specifications
as to position of shift lever, light on or off, air conditioner on or
off, vacuum line on or off, etc.
c. It is essential for good overall performance that the engine's
compression be good, the ignition points and timing be set correctly
and that the secondary ignition system, spark plugs, wires, etc. be
in good condition before starting to set mixture. Follow manufacturer's
recommendations when setting idle mixture, especially with emission
controlled vehicles.
MULTIPLE BARREL CARBURETORS
On multiple barrel fuel systems, there will be an idle jet screw for each
barrel. Simply adjust each screw individually to obtain the "Peak' RPM
before adjusting the other screw. It is usually necessary to then re-peak
the first and possibly re-peak the second due to interaction of jets and
manifolding.
ADJUSTING FAST IDLE SPEED
Some carburetors have a "fast-idle" adjustment screw which may be adjusted
as follows:
1.With engine running, open throttle and move the fast idle cam so fast
idle screw rests on the high step of the fast idle cam..
2. Turnthe fast idle screw to obtain specified fast idle speed as indicated
on appropriate scale of the tachometer.
AIR FUEL RATIO TEST
1. Remove the air filter.
2. With engine running and at its operating temperature, fix the throttle
with the idle speed screw to about 800 RPM.
J. Slide a flat plate slowly over the air intake of the carburetor, so as to
partially choke off the intake of air.
4. Watch the meter closely for any change in RPM.
5. Repeat the procedure in the above steps 3 & 4 at 1500 RPM and possibly at
about 2500 RPM.
TEST RESULTS:
a. Increase in engine speed indicates a lean mixture.
b. Decrease in engine speed indicates a rich mixture.
c. Little or no change in speed as the air intake is almost completely
closed off indicates an acceptable air-fuel ratio.
AIR FILTER TEST
1. Remove the air filter.
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2. Remove the windshield wiper hose or other accessory hose to purposely
create a lean mixture. |
3. Fix the throttle with che idle speed screw at about 800 RPM.
4, Put the air filter in place while watching the meter.
TEST RESULTS:
If engine speed decreases, inspect air filter for excessive dirt or damage
which may restrict air flow. Remember to re-attach the windowshield wiper
hose or other accessory removed for this test.
POSITIVE CRANKCASE VENTILATOR (PCV) TEST:
Becasue it is constantly exposed to the crankcase fumes and vapors which
can form gum and carbon, the PCV valve gradually plugs up and become
inoperative. An engine which is operated without proper crankcase ventilatio
can be damaged seriously. The system may be tested as follows:
l. Start the engine and let it idle.
2. Remove the PCV hose from the valve cover. Leave the other end connected
to the intake manifold.
J. Close off the end of PCV hose with your finger and note engine RPM.
TEST RESULTS:
a. If idle speed drops 50 RPM or more, crankcase ventilating system is
performing OK.
b. If idle speed drops less than 50 RPM, ventilator valve may plug up and
become inoperative. Clean or replace valve and PCV hose. After servicir
valve, re-set idle speed at manufacturer's recommendation for idle speec
CYLINDER POWER BALANCE TEST
This test determines if each cylinder of the engine is producing equal power.
Unequal power indicates problems in the ignition, compression or fuel system.
This test may be run before a tune-up to determine which cylinders have
problems, or afterwards to check if any individual cylinders have a problem
which you missed.
1. Set the engine speed at any steady RPM between idle and 1200 RPM.
2. Using insulated pliers, remove the ignition wire from each spark plug one
at a time and ground it to the engine bloc and reconnect each wire before
removing the next.
3. Record the engine RPM for each cylinder while the ignition wire is groundec
and compare these RPM readings.
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TEST RESULTS:
[f all readings are within 50 RPM of each other the engine has equal
power output from each cylinder. This indicates that no unusual Problems
exist in any one cylinder's ignition, compression or fuel system.
If one or more cylinders is more than 50 RPM different than the others,
check those with the highest RPMdrop. They have ignition, compression or fuel,
system problems that are causing those cylinder to produce less power than
the others.
On some late model (1971 and later American cars) with exhaust gas
recirculating type emission controls, this test will give erroneous
results. Some "good condition" cylinders will show no decrease or an
increase in engine RPM (consult service manual for this data).
с.
TRIBUTOR CENTRIFUGAL ADVANCE TEST
s test determines if the distributor” s mechanical advance mechanism is work-
ing properly.
1.
Set the engine to the lowest idling speed possible.
Loosen the lock screw of the distributor and rotate the distributor body
2.
slightly, left or right, until the mer. engine RPM is obtained. Hold
distributor in this position. .
3. Increase engine speed to approximately 1000 RPM and hold throttle in this
position.
4, Rotate the distributor again and note maximum increase in engine RPM.
TEST RESULT:
If the engine speed increases more than 100 RPM in the Step 4, the
distributor centrifugal mechanism is not working properly and the
distributor should be removed and the mechanism checked for binding,
wear or damage. After servicing, return the engine speed to correct idle
RPM and re-set the initial timing to the manufacture's specifications.
CAUTION:
Do not attempt to set initial timing by "peaking" RPM while turning
distributor. On late model, emission controlled vehicles this may lead
to overheating, diesealing and possible engine damage.
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DWELL
The dwell angle is the time the points remain closed during the ignition cycle.
Proper dwell allows the full build up of energy in the ignition coil for a good
spark at all engine speeds. Excessive dwell results in point burning and rapid
deterioration, while too little dwell reduces the available spark voltage
resulting in poor acceleration and missing at higher RPM. Always test and ad just
the dwell angle after either cleaning or replacing the ignition points and
before adjusting timing.
HOW TO USE DWELL ANGLE METER (See Fig. 4)
1. Move the function switch to DWELL position.
2. Move the cylinder switch (If supplied) to the number of cylinders required.
J. Connect the BLACK clip to a good engine or chassis ground.
4
. Connect the RED clip to the distributor terminal of ignition coil.
J. Start engine and let it idle.
6. Read dwell angle on appropriate meter scale.
NOTE: For perfect performance, consult specifications of the engine
~ manufacturer. Generally speaking, the normal dwell angle for 6 cylinder
engines is approximately 32 to 40 degrees. For 8 cylinder engines, the
dwell is approximately 25 to 32 degrees. For 4 cylinder engines, it is
twice the 8 cylinder engines.
NOTE: If dwell angle is too low, the point gap is too wide. If the dwell angle
is too high, the point gap is too low.
Fig. 4
NOTE: For positive ground
systems reverse the
RED and BLACK clip
connections
TO IGNITION
SWITCH
ADJUSTING DWELL ANGLE
Delco window type distributors (See Fig. 5): This distributor has an Allen screw
fitting so that the dwell angle can be set from the outside of the distributor
while engine is running. On these vehicles equipped with this type of distfibutor
simply lift the window protecting the Allen screw and adjust the angle to the
manufacturer's specification while observing the meter.
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Other. types of distributors with single ignition points (See Fig. 4): All
distributors where the poínt gaps must be adjusted from inside belong to these
types.
1. Remove the distributor's cap and rotor.
2. Loosen the locking screw of the ignition points.
3. Crank engine and turn the adjusting screw until the proper dwell setting is
obtained. At cranking speeds, the meter pointer will vibrate. Use the reading
half way between the extremes of the vibrating pointer as dwell angle
measurement. |
L. Re-assemble the distributor and check dwell with engine running. The dwell
angle may change slightly from cranking speed to running : re-adjust as
necessary.
NOTE: After proper dwell adjustment has been made, re-adjust the ignition
timing to engine manufacturer's specification. Any change in the dwell
angle will cause a change in the ignition timing.
DUAL POINT DISTRIBUTORS
Two types of dual point installations are in use. One has two individual points,
each independently controlling the coil. The other type uses two sets of ignition
points in parallel to extend the total dwell period. To identify: the first type
will ‘have a distributor cam with only half the distributor cam lobes as there
are cylinders. The second type will have the same number of distributor cam lobes
as cylinders. To adjust either type: always block open one set of points with a
clean piece of smooth card stock while adjusting the other set. After setting one
set, remove the card stock and move it to the other set and adjust remaining point
set. On vehicles with the points in parallel, after setting the point dwell for
each set, check that the total dwell is also within manufacturer's specification,
by removing the card stock and measuring the total dwell.
TESTING FOR DWELL VARIATION
Dwell variation (a change in the dwell reading as engine speed is increased) is
caused by wear in the distributor shaft's breaker plate bearings, or a bent
distributor shaft, Excessive variation may also be caused by worn linkage in the
vacuum or mechanical advance mechanism. To check the distributor for these
conditions perform the following test.
l. Follow the first 4 steps in HOW TO USE DWELL ANGLE METER.
2. Start engine and increase speed to about 1500 RPM,
3. Waléh the dwell meter on appropriate scale.
TEST RESULTS:
a. Dwell variation less than 3° or less than amount specified by the
manufacturer is acceptable.
b. It dwell variation is larger than specified, check distributor plate
and bearings for wear.
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+ On distributor where breaker plate assembly pivots around distributor
shaft, check bearing surface of breaker plate and shaft and for looseness
in vacuum advance linkage,
‚ On distributor with off-center pivots, which normally have high dwell
variations specified, check also for binding or wear of bearing points
between breaker plate and bottom plate of distributor.
SERVICE:
IN THE UNITED STATES MAIL TO:
Make Waves Instrument Corporation
4444 Broadway
Buffalo, New York 14043
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